<?php

require_once 'HTMLPurifier/ChildDef.php';

/**
 * Custom validation class, accepts DTD child definitions
 * 
 * @warning Currently this class is an all or nothing proposition, that is,
 *		  it will only give a bool return value.
 * @note This class is currently not used by any code, although it is unit
 *	   tested.
 */
class HTMLPurifier_ChildDef_Custom extends HTMLPurifier_ChildDef
{
	var $type = 'custom';
	var $allow_empty = false;
	/**
	 * Allowed child pattern as defined by the DTD
	 */
	var $dtd_regex;
	/**
	 * PCRE regex derived from $dtd_regex
	 * @private
	 */
	var $_pcre_regex;
	/**
	 * @param $dtd_regex Allowed child pattern from the DTD
	 */
	function HTMLPurifier_ChildDef_Custom($dtd_regex) {
		$this->dtd_regex = $dtd_regex;
		$this->_compileRegex();
	}
	/**
	 * Compiles the PCRE regex from a DTD regex ($dtd_regex to $_pcre_regex)
	 */
	function _compileRegex() {
		$raw = str_replace(' ', '', $this->dtd_regex);
		if ($raw{0} != '(') {
			$raw = "($raw)";
		}
		$el = '[#a-zA-Z0-9_.-]+';
		$reg = $raw;
		
		// COMPLICATED! AND MIGHT BE BUGGY! I HAVE NO CLUE WHAT I'M
		// DOING! Seriously: if there's problems, please report them.
		
		// collect all elements into the $elements array
		preg_match_all("/$el/", $reg, $matches);
		foreach ($matches[0] as $match) {
			$this->elements[$match] = true;
		}
		
		// setup all elements as parentheticals with leading commas
		$reg = preg_replace("/$el/", '(,\\0)', $reg);
		
		// remove commas when they were not solicited
		$reg = preg_replace("/([^,(|]\(+),/", '\\1', $reg);
		
		// remove all non-paranthetical commas: they are handled by first regex
		$reg = preg_replace("/,\(/", '(', $reg);
		
		$this->_pcre_regex = $reg;
	}
	function validateChildren($tokens_of_children, $config, &$context) {
		$list_of_children = '';
		$nesting = 0; // depth into the nest
		foreach ($tokens_of_children as $token) {
			if (!empty($token->is_whitespace)) continue;
			
			$is_child = ($nesting == 0); // direct
			
			if ($token->type == 'start') {
				$nesting++;
			} elseif ($token->type == 'end') {
				$nesting--;
			}
			
			if ($is_child) {
				$list_of_children .= $token->name . ',';
			}
		}
		// add leading comma to deal with stray comma declarations
		$list_of_children = ',' . rtrim($list_of_children, ',');
		$okay =
			preg_match(
				'/^,?'.$this->_pcre_regex.'$/',
				$list_of_children
			);
		
		return (bool) $okay;
	}
}

